Biofilms are mucilaginous communities of microorganisms such as bacteria, archaea, fungi, molds, algae or protozoa or mixtures thereof that grow on various surfaces (see Nature, vol. 408, pp. 284–286, Nov. 16, 2000). Biofilms form when microorganisms establish themselves on a surface and activate genes involved in producing a matrix that includes polysaccharides. This matrix may provide protection of biofilm bacteria from biocides.
Molecules called quorum-sensing signals help trigger and coordinate part of the process of forming a biofilm. Bacteria constantly secrete low levels of the signals and sense them either through receptors on their surfaces, or internally. The receptors trigger behavioral changes when there are enough bacteria to allow the signals' concentrations to achieve a critical threshold. Once this occurs, bacteria respond by adopting communal behavior, such as forming a biofilm, and in the case of pathogenic bacteria, deploying virulence factors such as toxins. In addition to communicating with members of their own species, bacteria also conduct inter-species communications, such that a biofilm may contain more than one species of bacteria.
Biofilms are frequently undesirable. For example, biofilms cause damage by coating equipment such as cooling systems, or aquaculture equipment. Biofilms can also have detrimental health effects. For example, many hospital-acquired infections involve biofilms, which can contaminate implants and catheters. Dental lines are prime candidates for biofilm formation. Biofilms also cause diseases ranging from lung infections in cystic fibrosis patients to tooth decay.
However, biofilms can also be desirable. For example, biofilms are used in bioreactors used for such tasks as manufacturing pharmaceuticals, and biofilms are also components in sewage and other water treatment systems.
One method for preventing or disrupting a biofilm is to interfere with the quorum-sensing signals. Chemicals have been developed that bind but fail to activate the receptors of quorum-sensing signals or that interfere with signal synthesis. Enzymes that degrade the signals have also been developed. Certain quorum-sensing signals typically have acylated homoserine lactone ring systems. WO 00/06177 reportedly provides methods for identifying modulators of the autoinducer synthesis reaction that promote or inhibit production of homoserine lactone. WO 00/32152 reportedly provides a bacterial signaling factor 4,5-dihydroxy-2,3-pentanedione, wherein the factor assists in inducing expression of luminescence genes.
There is an ongoing need to identify agents that modulate biofilm formation and growth, as well as methods and devices for testing such formation and growth. The present invention addresses these problems and provides certain nitrogen heterocyclic molecules that modulate such processes, as well as methods and devices for testing such modulation.